Closes https://github.com/dart-lang/sdk/issues/25324
requestFullscreen returns a Promise and takes in an options parameter.
It also can be accessed either via `requestFullscreen` or
`webkitFullscreen` (only necessary for Safari). The bindings should be
updated to reflect this behavior.
Change-Id: I9401b6a1c8b3f9ac370aad8caac8295e0ee358b8
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/229381
Reviewed-by: Sigmund Cherem <sigmund@google.com>
Commit-Queue: Srujan Gaddam <srujzs@google.com>